1. Field of the Invention
The present invention relates in general to an electrochemical biosensor strip. More particularly, the present invention relates to an electrochemical biosensor strip that has a hydrophilic layer laid under a test reagent and excluded from an electrode system corresponding to the test reagent for increasing the test reagent binding on a base and preventing the hydrophilic layer interfering with signal transmission.
2. Description of the Related Art
Since the improvement of the science and technology, many tests can be operated by users in house. In the market, many disposable strips are used for measuring specific components in a biological fluid and can be operated by users in house. Analytical biosensor strips are useful in chemistry and medicine to determine the presence and concentration of a biological analyte. Such strips are needed, for example, to monitor glucose in diabetic patients and lactate during critical care events. Biosensor strips are used in the chemical industry, for example, to analyze complex mixtures. They are also used in the food industry and in the biochemical engineering industry. Biosensor strips are also useful in medical research or in external testing. In external testing, they can function in a non-invasive manner (i.e., where they come into contact with blood withdrawn by a syringe or a pricking device).
Conventional electrochemical biosensor strip has a base, an electrode system, an insulating substrate, a test reagent and a cover. The electrode system is laid on the base and comprises two electrodes separated from each other. The insulating substrate is laid down onto the electrode system and has a first opening and a second opening. The first opening exposes portions of the electrode system for electrical connection with a meter, which measures some electrical property of a test sample after the test sample is mixed with the test reagent of the strip. The second opening exposes a different portion of the electrode system for application of the test reagent to those exposed surfaces of electrode system. The test reagent is a reagent that is specific for the test to be performed by the strip. The test reagent may be applied to the entire exposed surface area of the electrode system in the area defined by the second opening. The cover is covered on the electrode system and the test reagent for protecting the test reagent.
However, since the base is prepared by polyethylene terephthalate (PET) or polyvinyl chloride (PVC) which is hydrophobic, the test reagent laid on the base is unstable. The strip is manufactured by a sheet of the PET or PVC substance and the sheet is cut for forming multiple strips after every needed substances are laid on the sheet. When the cutting step is proceeding, the test reagent is easy to shake off from the base. Besides, the electrode locates on the base so as to protrude from the base such that a surface that the test reagent layer laid on is not a flat plane. It will cause the test reagent spread on the base unequally so as to interfere with the detecting result.